When an Ender Dragon dies because of the explosion of a healing Ender Crystal, the healing animation will still stay until the Ender Dragon is "gone".

How to reproduce:

/summon PrimedTnt ~ ~ ~ {Fuse:20,Riding:{id:EnderCrystal,Riding:{id:EnderDragon,Health:0.05}}}

I highly recommend to do this in an extra world and not in a normal survival or creative world because of the explosion of the Ender Crystal and the Ender Dragon