boli

Boli is intransitive, and that single fact is the whole lesson of this page. The water does the boiling; nobody boils it. So la akvo bolas is correct and *mi bolas la akvon is not a sentence, however natural the English I boil the water sounds.

To put a cook back into it, add -ig-, the suffix that makes an intransitive verb transitive: mi boligas akvon por la teo, I boil water for the tea. The pair is exact and worth learning as a pair.

English hides this distinction because one verb does both jobs, which is exactly why English speakers get it wrong here and nowhere else. The machinery is set out in igi and iĝi, and the question of which verbs need it is transitivity. There is no *boliĝi: boli is already the intransitive one, so adding -iĝ- would be asking the water to start boiling itself twice.

Around it: bolanta is boiling as an adjective, bolpunkto the boiling point, bolkuiri to cook by boiling, and the figurative sense works exactly as in English, so a crowd, a temper or a sango can all boli.