The formation of gas bubbles in glass at high temperature 

GT_V3_1962_124-129

When glass is reheated gas bubbles may form within the glass; this phenomenon is often referred to as reboil. Some glasses are much more inclined than others to show this instability, and the object of this work has been to determine factors that affect the stability of glass towards this type of thermal decomposition. In all glasses the water content was found to be important. In reduced carbon-sulphur amber glasses an additional factor which controlled reboil stability was also found to be present.

S. M. Budd, V. H. Exelby & J. J. Kirwan