boil something down—(coll.) state smth. briefly; summarize smth.:
- I have tried to state briefly, to boil down, the most important area of conflict.
boil something up—
1. boil or wash clothes:
- There was a grand jungle by a small, clean river where they boiled up their verminous clothes.
2. make tea:
- In modern India, tea is usually boiled up very strong with milk and lots of sugar.
Note: The expression does not correlate in meaning with the phrase bring something to the boil—cause smth. such as a problem to reach an urgent state:
- Issues concerning the intellectual property rights have been simmering since the 1990s. Developments in communications technology have brought these issues to the boil.
Cf.: go off the boil—(coll.) cease to be active or interesting:
- The housing issue has gone off the boil recently, despite attempts to revive public interest.