Hi Jay you said " How do you know that those Chinese LED bulbs are not designed to do that (explode)? "
I think they may have been. Really spectacular explosion. The clear glass cover was blown off the fitting (big bang) and bounced off the ceiling . The inside of the glass shroud has vapourised meal deposits on it. Wife has banned me from fitting more "direct from China" Ebay bulbs. Interestingly I can't find that type of LED bulbs any anywhere on Ebay.