bathtub explosion

“Stop, Stiyl!! If you stab your flame sword into the water, the bath will boil!!”
Lola practically fell out of the bathtub as she escaped. In the next instant, the water did
not just boil; it underwent a slight phreatic explosion. The archbishop lay on the wet
floor, opening and closing her mouth as she gasped for air. Her long, long hair was
wrapped around her like a cocoon, making her look like some kind of monster.

- Toaru Majutsu no Index Volume 12, Between the Lines 1