boil down—be reduced by boiling:
- These plums are heaped up in the pan, but they will boil down.
boil up —(of a quarrel, crisis, etc.) develop; be about to occur:
- A dispute is boiling up over who should be the first to greet our royal visitors.
boil down—be reduced by boiling:
boil up —(of a quarrel, crisis, etc.) develop; be about to occur: