There are tiny stones and other impurities (commonly known as "sulfur") in the original glass sheet of the float glass manufacturer itself, or the tempered glass is subjected to improper external force from the user, which leads to bursting. This phenomenon is inevitable, even the best brand manufacturers dare not say that tempered glass will not explode, but will try to reduce the probability of self-explosion.
In addition, according to your description, the glass has a key point, and it does not rule out that someone vandalized it or just played a prank, which is unknown.
This phenomenon has nothing to do with luck, please rest assured.