Dramatic Disappearing Display

This is the thing where, during a climactic Boss Battle or event in a Video Game, the game's display (showing Score, the Life Meter and such) vanishes away, leaving a completely unobstructed view of the game area. Presumably, something so awe-inspiring and theatrical is about to happen that it deserves the player's complete attention, as if it were a Cutscene.

...Or it could just be due to technical limitations preventing both the display and the large animated segments of the boss from being displayed simultaneously. And, yes, the majority of these examples seem to be on 8-bit systems. ...Believe what you want to believe!

Action Adventure Games

 * Ico.
 * The final battle in Legacy of the Wizard has only your life and the bosses' life shown. But since your item selection is in the HUD, you can't choose a healing item after you've started.
 * Enslaved: Odyssey to the West inverts this, with no HUD during the first mission, and the HUD appearing after an advanced headband is wired directly into your brain by the support character.

Action Games

 * Metal Gear Solid 4: Guns of the Patriots mostly averted this trope in the final boss battle, actually drawing attention to the HUD by changing it to be similar to each previous game in turn. However for the final climatic punches the HUD disappears completely.
 * God of War III has a Dramatic Shattering Display at the endgame, after which the only HUD elements are for Press X to Not Die (IE: there's no more actual combat from that point onwards).

Driving Games

 * This is an option in Initial D Arcade Stage ver. 3; you can choose between the full HUD, or a simplified HUD that only displays the most vital information using a smaller font.

Fighting Games

 * The Final Boss battle against Suika Ibuki in the first Touhou fighting game, Immaterial and Missing Power, does this gradually when Suika uses her final spell card.
 * Activating Astral Heat in BlazBlue: Continuum Shift will cause the background to go black. And except for Carl and Arakune, successfully scoring a hit with Astral causes the HUD to disappear.
 * Fatalities in Mortal Kombat 9 causes the far background to go black and the HUD to disappear as well.

First-Person Shooter

 * Halo does this. The HUDs disappear, and the widescreen crop widens out.
 * Some games, like Jurassic Park: Trespasser and Peter Jackson's King Kong, have no HUD at all.
 * Half-Life 2 does this from time to time, usually when the G-Man or Combine Advisors get involved.
 * In most Half-Life mods, the HUD is never hidden when the camera is used. Some mods like Afraid of Monsters (DC only) uses black widescreen barriers to hide the HUD for a more cinematic feel.

MMORPGs

 * The final cutscene in Chains of Promathia completely removes the HUD for the first time in the game's history, and throws in some Crowning Music of Awesome for the heck of it.

Platform Games

 * The Bowser battle in Super Mario World for Super NES. Only the powerup box at the top of the screen remains, and only if it contains a powerup. Tiled background planes can't overlap rotating (mode 7) background planes.
 * Amusingly subverted in the GBA version—it begins with no display just like in the SNES version, though if you brought a reserved item into the battle, it suspiciously won't show up. After Bowser comes out of the Clown Car for the first time, however, the display suddenly drops down from the screen. You even get a final score tally for beating him!
 * The last battle of Donkey Kong 94.
 * Worlds X-7 and X-8 in Eversion. Though if you're in time attack mode, none of this applies; the timer (which is the only part of the HUD in that mode) will remain at the top of the screen at all times.
 * The Game Gear version of Sonic the Hedgehog omitted the HUD during each Zone's third Act (where you fought Robotnik). There are zero rings during boss battles anyway.
 * The Trope Codifier for Dramatic Appearing Displays would be the first Donkey Kong Country.
 * The final battle in Extra Mario Bros.
 * Demon's Crest turns it around. During the sudden boss fight at the very beginning of the game, you have no HUD, but Firebrand can still only take four hits before dying. After fighting off the boss once and escaping, your HUD appears, and any damage Firebrand took will remain.
 * Bug!! has the bonus levels, where your entire HUD disappears (save for a timer in some bonus levels). Then again, you're a One-Hit-Point Wonder in all bonus levels, and getting hit will make you exit. Also, when Bug dies, the HUD disappears too.

Rhythm Games

 * A few songs in DJMAX Portable Clazziquai Edition and Black Square have the game interface vanish to show the entire video, typically at the end of the song. Both parts of the song "Proposed, Flower, Wolf" have the interface remain off for large portions of the song.
 * Guitar Freaks and Drummania have a modifier called "Dark" that hides all non-vital elements ("vital" being stuff like the notes, the score display, and your Life Meter) of the game interface.

Role-Playing Games

 * In Raidou Kuzunoha vs. the Soulless Army, when you're about to get a critical piece of information, sometimes, not only do the moon phase and encounter imminence displays vanish, but the screen develops letterboxing bars. Definitely the game going, "Pay attention to this!"
 * Bosses in Final Fantasy XII tend to have a flashy attack that takes away the interface and essentially displays a short Cutscene. Really important bosses will have more than one.

Shoot'Em Up

 * Most stage-end bosses in the Famicom versions of Gradius II and Life Force.
 * All except the last two bosses in the Famicom Shoot'Em Up Recca.
 * A partial (but nice-looking) example is seen in the manic shooter Dangun Feveron. When a boss battle starts, most of the upper HUD (rescue count, score display, high score) slides off the top of the screen to make room for the boss's health bar, leaving only the important things- your remaining bombs and lives. When you defeat the boss, its lifebar goes off the screen and the normal HUD comes back.
 * Hero Core and predecessor Hero flash the scenery around Cruiser Tetron and make it disappear before you start to fight him.
 * In R-Type Final,  breaks the Charge Meter.

Simulation Games

 * In The Sims 2, the screen zooms in on a Sim who has their 1st kiss, or sex, or has a baby, and the character's needs and character selection bar disappears.

Stealth-Based Games

 * During the fight against Metal Gear D in Metal Gear 2: Solid Snake: Solid Snake, the HUD disappears. This was done because of sprite limits - animating Metal Gear was very intensive.
 * When you are low on Synchronization in Assassin's Creed the Animus interface vanishes to let you know that one more hit Will Kill You.

Survival Horror

 * The early Resident Evil games had no on-screen HUD, and the only way to check your health and ammo was to pause. Code: Veronica had a health indicator through the Dreamcast's controller, but still nothing on screen. It wasn't until the fourth game that you had any sort of HUD at all, and initially they were going to have it only flash when you were damaged.

Turn-Based Strategy

 * This is a default in some Super Robot Wars games, given the games' focus on fidelity and over-the-top-itude; units' HP and EN bars will slide out of the way for the duration of the attack animation. When they don't, it's usually because (as in the console iterations) the attack will appear to deal a portion of its damage to the health bar with each hit.