Boil Release (沸遁, Futton; Viz "Vapour Style") is one of the two advanced naturekekkei genkai of Mei Terumī and is made up of techniques that combine fire and water-based chakra to create a powerful corrosive vapour capable of melting anything. The user is also able to control the range and level of the vapour's acidity.
This technique is strong enough to melt Susanoo's ribs; an impressive feat, as Sasuke has stated that Susanoo is even more of an absolute defence than Gaara's Shield of Sand.
Despite the name of this nature, it does not manipulate boiling water, nor does it boil other things. The name is more symbolic, representing the names of the natures used to create this nature. It is also symbolic of the appearance and effect of this nature, as the corrosion seen is similar to hot water burning something.