Why would a glass sliding door shatter spontaneously?

Why would a glass sliding door shatter spontaneously?

Window expert, says that pre-existing damage and imperfections are both factors in the doors’ spontaneous shattering, but what else could possibly caused this breakage. Spontaneous¬†glass breakage¬†is a phenomenon by which toughened glass (or tempered) may spontaneously break without any apparent … (read more)