Death by Cauldron in Dante's Inferno

The idea of immersion in some kind of liquid being a transformative process, and the process of baptism. A lot of modern ideas about the christian hell are from dante's inferno. And beyond hell e, you get into the idea of purgatory, et cetera. Most notably there is the river of a plegathon, which is literally a river of boiling blood in which the souls of the damned writhe.