Lava Boost

When Mario comes into contact with lava and he's in a ground state, he gets burned and does a jump (lava boost). This jump is pretty big and can be used to skip some puzzles or get to places faster. This is also useful for Vertical Speed Conservation as if mario lands as soon as possible, he gets a big amount of Vertical Speed Stored (80.8 units/frame is the maximum).

If you are looking for the trick in the volcano, see Volcano Lava Boost.