When you power a piston that is directly next to an ender crystal, the ender crystal appears to be pushed but actually is not. After reopening the world, the ender crystal appears at the position of the fire.
This can also cause the crystal to explode: https://www.youtube.com/watch?feature=player_detailpage&v=aXOCEnAPOks#t=180
- Place a piston
- Place an ender crystal next to the piston that the piston is facing the crystal
- Power the piston
- The ender crystal will appear to move, but summoning an armor stand at its location will reveal that it didn't actually move
Can also be reproduced using shulkers.