There are so many different kinds of explosions too. The often unrealistic and overused effect in Hollywood is the fiery explosion, but this is usually the result of a volatile source like barrels of gasoline. However watching grenades go off is a totally different effect. In this column will cover what goes into an explosion and how that ties in with creating synthetic ones. It doesn't really matter what 3D package you use to make the effects as the techniques are not platform specific.
All explosions happen for a reason.
Either way it all begins with a flash. The intensity of the flash is usually proportional to the size and heat of the blast. Notice how the sky lights up like a small sun and lingers for bit when a nuclear weapon is detonated. On the flip side, light a firecracker and you'll just get a quick flash. One way of producing the flash is with a post effect like a glow or flare.