boil up
US /bɔɪl ʌp/
UK /bɔɪl ʌp/

1.
hervir, aumentar
to become very angry or excited
:
•
His anger began to boil up when he heard the news.
Su ira comenzó a hervir cuando escuchó la noticia.
•
Tensions are starting to boil up between the two groups.
Las tensiones están empezando a aumentar entre los dos grupos.