Technically, they were evaporated before liquifying. The incoming water does so with so much force and speed that the air in the boat retains its heat but is compressed extremely fast, so the temperature rises sharply until ignition. Someone in the posted sub did the math, about 1100 degrees celsius were reached. So they went poof like in a diesel engine a few micro seconds before the water mushed everything together.

But yeah, too fast to feel or notice anything.