Corrosive fluid discharge

Bombardier beetle: "A bombardier beetle produces and stores two reactant chemical compounds hydroquinone and hydrogen peroxide in separate reservoirs in the rear tip of its abdomen. When threatened, the beetle contracts muscles that force the two reactants through valved tubes into a mixing chamber containing water and a mixture of catalytic enzymes. When combined, the reactants undergo a violent exothermic chemical reaction raising the temperature to near the boiling point of water. The corresponding pressure buildup forces the entrance valves from the reactant storage chambers to close, thus protecting the beetle's internal organs. The boiling, foul-smelling liquid partially becomes a gas (flash evaporation) and is expelled through an outlet valve into the atmosphere with a loud popping sound."