I usually use either a lot of spheres with a volume or fuzzy texture and I use the a 3d disperse option to animate it. fuzzy textures render faster then volume ones so I prefer using those. I've also made a more stylish explosion once using animated volume textures. This one here in the image is one 2D-plane with a shockwave texture rendered from a flattened sphere with a volume texture animated in the DTE. and one sphere for the spherical shockwaves. Also animated in the material lab and the DTE.

(_/)
(='.'=)
(")(")This is Bunny. Copy and paste bunny into your signature to help him gain world domination.