Heated to the point of bubbling; heaving with bubbles; in tumultuous agitation, as boiling liquid; surging; seething; swelling with heat, ardor, or passion.(adjective)
source: webster1913
noun (n)
the application of heat to change something from a liquid to a gas(noun.process)
source: wordnet30
cooking in a liquid that has been brought to a boil(noun.act)