Explosions don't really have much to do with fire, but more to do with creating lots of gas from solids very quickly. Of course, fire is usually involved as a good way of doing this! The pressure that they create in a small volume makes them extremely hot, too, so there's usually fire at least indirectly.

Some things are very dense with energy and can be made to violently and quickly transform into another thing without that change of state, but they don't really explode.

Mundane uses for explosion technology where fire isn't involved (hopefully!) is in car airbags. They use sodium azide which decomposes on heating (even slightly, that's why you keep it in the fridge) to release masses of nitrogen to inflate the airbag.