According to the ancient Roman writer Pliny, this is how the
Phoenicians discovered how to make glass:

A group of Phoenician sailors had gone and acquired a cargo of
nastrum. It is a subcarbonate of soda. The ship stopped at the
Phoenician coast and the sailors went ashore to make dinner. They
were at the mouth of the Belus River. The sailors could not find any
stones to prop up their cooking utensils. They decided to use one of
the blocks of nastrum and it mixed with the siliceous sand at the
base. Thus a stream of glass was formed. The Phoenician sailors
realized that they had accidentally discovered a technique for making
glass.
We do not know if this story is true, but it is plausible. It is
certainly not impossible.

Neal Robbins