Ghast disappearing?

Hi!
I noticed today when I were in the nether to kill some ghasts that they sometimes just disappear
I shot the ghast a couple times and then it disappeared
And this happens pretty often
Is it like a bug or something?

Can anyone answer please?

I wish they would disappear ... I hate them! I killed a few today though, and never had this problem. Sorry.

I love em
But this problem happens really often and i wonder why?
It's so frustrating!

It may be that they died but glitched out ?

Don't think so.....
Sometimes they disappear even if I have hit them with arrows or not

Well, any hostile mob that is more than 32 blocks away from you is close to despawning, and it is possible that they are spending too much time outside of that radius and being despawned by the server. Of course, if you get 128 blocks away from them they will despawn immediately, though I don't think that is the culprit.

Same thing happens to me in SSP, creepers just up and vanish without even a tiny explosion