User blog comment:Lord Loss/Monster Hunter Theory... Blog/@comment-5020152-20120609204957/@comment-72.136.163.92-20120611181734

Some fungus actually produce hydrogen peroxide through decomposition. (Could be the fungus that grows inside its body.)

"Above roughly 70% concentrations, hydrogen peroxide can give off vapor that can detonate above 70 °C (158 °F) at normal atmospheric pressure" taken from wikipedia. (Sounds like MH volcano to me)