Extraordinary claims. Ordinary investigations.

Pouring molten glass on cold water, you can get Prince Rupert’s drops, named after the fellow who discovered the process around the 17th century. The quick solidification of the glass in the outer layers creates strong internal tension, distributed on a peculiar way and assuring the “magic” effect.

Drop a hammer over the bulbous end, and it will remain intact. But create a small fracture by the thinner end, and the drop will instantly explode into glass dust.

The same principle is applied in tempered glass, which combines greater resistance with almost instant fragmentation when the internal tension is broken. Another video below: