Pyrex is the trade name of a Corning low thermal expansion glass. All Pyrex is glass, not all glass is Pyrex.

The boiling water causes the inside surface of the thick glass to expand rapidly. But the outside of the glass expands at a much slower rate, as it takes time for the heat from the inside to reach the outside, and the expansion to equalise. It is this difference in expansion that can cause the glass to break.

Unfortunately, this depends upon whose Pyrex you are considering. The original Pyrex was a borosilicate glass, which has a low thermal expansion. The Trademark owners have allowed the name to be used nowadays by some manufacturers who use tempered soda-lime glass. But some licensees still use a borosilicate glass.

Consumer Ultra-Low Voltage was created in 2009.

Quartz glass