boil over
[verb]
Synonyms: anger, blow up, boil, bristle, burn, flare (up), fume, rage, seethe

[TahlilGaran] English Synonym Dictionary ▲

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.

[TahlilGaran] Dictionary of Contemporary English ▲

boil over
to become uncontrollable.
Anger boiled over when the police ordered the protesters to leave.

Etymology: based on the idea of liquid in a pan being heated until it boils over the side of the pot

[TahlilGaran] English Idioms Dictionary ▲

boil over
v. phr.
1. To rise due to boiling and overflow down the sides of a pan or a pot.
"Watch out!" Jane cried. "The milk is boiling over on the stove!"
2. To become enraged to the point of being unable to contain oneself.
John took a lot of abuse from his boss, but after 25 minutes he suddenly boiled over and told him what he thought of him.

[TahlilGaran] English Idioms Dictionary ▲