boil up
US /bɔɪl ʌp/
UK /bɔɪl ʌp/

1.
ribollire, montare
to become very angry or excited
:
•
His anger began to boil up when he heard the news.
La sua rabbia cominciò a ribollire quando sentì la notizia.
•
Tensions are starting to boil up between the two groups.
Le tensioni stanno iniziando a ribollire tra i due gruppi.