Pre-Explosion Buildup

Before a big explosion, there is a very short buildup towards the explosion, this is done more for the awe effect and usually doesn't actually have any meaning or explanation, audible and visible to the viewer, but not necessarily a part of the universe. If a bomb literally needs to build up power before it explodes then it probably isn't a part of this trope, especially not if it takes a while. (though it could be)

Often only takes a second, before the big boom, you will hear a very soft sucking sound, or a warping sound. In some more exotic examples, the sound will temporarily disappear. Sometimes accompanied by a Pre Explosion Glow. Or a visible ripple and warping effect in the surroundings or the bomb will be shown Sucking in Lines.

Film

 * In one of the Star Wars prequels, Jango Fett uses "seismic charges" against Obi-Wan. Before they explode, there is a second of complete silence. Even the audible silence of space stops for a moment.
 * Krypton exploding in Superman Returns uses this effect.
 * The Matrix is a heavy user of this trope. Justified to some extent as a side-effect of the Matrix's processors being unable to keep up with the unanticipated actions of the heroes.
 * In the first movie, the glass warped visibly and audibly when the helicopter crashed into the building.
 * There was a short silence before the EMP went off.
 * In the second movie, warping effects when Neo exited the bomb wired level with all the doors.
 * Also when the power plant was blown up.
 * In The Lord of the Rings:The Return Of The King, this is heard before the big green bolt of garrison-light bursts out of Minas Morgul towards the sky, while Sam, Frodo and Gollum watch (and listen) in horror and the Witch-King flies out towards the siege of Minas Tirith.
 * Terminator 2 had the dream sequence where Sarah Connor imagines herself getting killed by a nuclear weapon fired by Skynet: First there is a blinding light and a heat wave, causing the everything to catch fire. Then comes the shockwave with accompanying sound and mushroom cloud, which flattens buildings, throws cars around, uproots trees and causes the scarred remains of people to scatter into the air like leaves.
 * Watchmen uses this with where the sphere of Applied Phlebotinum shrinks into nothingness and is followed by the blast a moment of silence later.

Literature

 * The Hitchhikers Guide to The Galaxy: "There was a terrible ghastly silence. There was a terrible ghastly noise. There was a terrible ghastly silence."
 * Your Mileage May Vary on whether that counts since it could just be a subversion of noisy space.

Live Action TV

 * Star Trek is also a big offender. A variety of effects are used for different explosions.

Video Games

 * When Tyreal blows up the Word Stone in the epilogue of Diablo II: Lord of Destruction, a warping sound can be heard before the stone goes boom.
 * In fact, this effect is tripled:
 * There is a moment of silence after Tyreal charges up the sword (and a slowmotion effect when he throws it) that reaches its pinnacle when the words enters the stone. Then the dimensions around the stone start to ripple.
 * The stone slowly disintegrates, and as it reaches its ends, it builds up to a final explosion, this explosion is preluded by the now familiar pre-explosion warping sound.
 * But then it turns out that there is a second, even louder explosion, that comes after a softer explosion, the softer explosion thus itself becomes the pre-explosion warp.
 * Also present in Halo 3. When a Covenant vehicle is destroyed (except for Brute manufactured ones) it will explode once then almost invariably produce a strange whine and explode again. This is justified as the vehicle's plasma coil going critical.
 * The fate of the evil space ship in the finale of Elite Beat Agents.
 * Star Fox 64 has a remarkable numerical example when unlocking the hard path from Macbeth.

Web Original

 * During missions for the Protectors of the Plot Continuum, Canon Analysis Devices that are exposed to too much OOCness will usually display gibberish before burning out.

Western Animation

 * In Titan AE the Drej Planet Killer first turns on a targeting/focusing beam, then hits the planet with an energy burst, causing shockwaves to ripple around the planet surface while the seas boil and the continents burn, and finally the entire planet erupts like a volcano, shattering it to tectonic-plate-sized pieces.