This theory is a
I've a theory on how the Qurupeco creates flames and explosions. I propose that the Qurupeco creates a noxious liquid in a gland somewhere in its chest, which is extremely flammable, comparable to petroleum, gasoline, or oil. When it clicks its flints together, it creates a spark big enough to ignite this when the Qurupeco vomits it up.
However, when the liquid is spat on a living thing, the living thing gets very flammable, which explains the "Fire element defense down" spit.