Jungle
It would sink to the bottom before kicking itself out of the poison slowly.
Beach
As soon as it touches water, it'll slowly float upwards before launching itself higher (This process is slightly faster than Poison.)
Volcano
It would rapidly strike upwards while playing the fire death particle and burnt SFX from Players.
The big star would enter in it's I-Frames mode when inside any of the liquids, so walls, or any other ground don't get on it's way.
This mechanic will boost up games and prevent big stars from despawning in a way players don't have a risk of dying.