Where does “kuumentuminen” come from?

kuumentuminen (Finnish) comes from Finnish -minen, from Proto-Finnic -minen, from Proto-Finnic -ma, from Proto-Uralic -ma.

Ancestry of “kuumentuminen”, step by step

Step	Language	Word	Meaning
1	Finnish	-minen	Forms verbal nouns from verbs, mostly corresponds...
2	Proto-Finnic	-minen	Forms nouns from verbs, indicating the action of...
3	Proto-Finnic	-ma	Forms action/result nouns from verbs; Forms the...
4	Proto-Uralic	-ma	—