Apple has guts...

[WilliamG]

I can't explain your exact circumstance, but it behaves exactly how it does on OS X.

I've never had this happen in OS X..

 

[xraydoc]

Obviously the underlying issue is RAM. However, this is about whom Apple chooses to BLAME when its device becomes RAM starved. That's what I find underhanded.

As stated by others, it also periodically happens on my iPad Air 2 (2GB of RAM), even with no other tabs open. So I don't necessarily think it's just a RAM issue. Personally I think there's a render bug in Safari for iOS 8.