BOIL OVER

boil over phrasal verb ( see also ↑ boil )

1 . if a liquid boils over when it is heated, it rises and flows over the side of the container:

The milk was boiling over on the stove behind her.

2 . if a situation or an emotion boils over, the people involved stop being calm:

All the bitterness of the last two years seemed to boil over.

boil over into

Anger eventually boils over into words that are later regretted.