When I spawn endermen onto magma blocks, they take damage and teleport away, but continue to take damage, make sound from the location they teleported from, and eventually return quickly in the fashion of any other mob that, say, lagged through a wall. When they die, even if the model fell over somewhere else, the white smoke is emitted from the original location. For whatever reason, they look like they're teleporting away but actually aren't. This is in an unmodded single player world.