Bang

Two layers of smoke are used in this project. The lower "smoke stay" is affected by Physics>Air Resistance so it stops after a while. The second "smoke up" also uses Air Resistance, but has a Wind Y value of -100 so it keeps moving upward, even after the air resistance has stopped it. Both smoke layers only emit particles at the first few frames - this can be seen by inspecting the keyframes on the Particles/sec parameter. Using two layers increase realism and flexibility.

Sparks are added for further realism. They are also emmitted in a burst at the beginning of the comp. Because they move so fast and use motion blur, they look like tiny lines.

Since explosions are so bright, they normally create lens flares. In this project, a lens flare was added and the Flare Center and Flare Brightness was keyframed to create a flickering moving flare which makes the rest of the explosion look more real.