To boil something in hot water (e.g., eggs or vegetables).
卵を10分茹でてから冷水にとる。
Boil the eggs for 10 minutes, then put them in cold water.
野菜はさっと茹でてからサラダに入れると色がきれいだ。
If you briefly boil vegetables before adding them to a salad, their color stays bright.
じゃがいもを柔らかくなるまで茹でる。
Boil the potatoes until they become soft.
To treat a swelling or lesion with medicinal steam (to apply hot steam or warmth); a rarer/older usage.
民間療法で患部を湯気で茹でることがあるが、専門家に相談するべきだ。
In folk remedies people sometimes treat an affected area with steam, but you should consult a professional.