User blog comment:Plexioth- xD/Monster Hunter 3 Ultimate/@comment-24.218.161.23-20121017200437/@comment-4212769-20121018132124

Or the summary:

It's not actually the "fire" or "heat" that damages with an explosion but the pressure that the gas that is produced exerts as it needs more space than solids (gunpowder) or liquids (nitroglycerin).