So, just an idea pitch. The bombardier beetle utilizes the reaction of two chemicals to create a nearly 100 °C liquid that's sprayed in the face of its enemies. How that doesn't damage the beetle? I place my bet on the Leidenfrost effect.
But, can a living creature "do better"? More precisely, I'm looking for chemicals that could replace hydroquinone and hydrogen peroxide and when mixed together, produce more heat and higher temperatures.