If your glass is exploding it may not be borosilicate (COE 33).
Either this or you are heating/cooling unevenly.
Heat around the tube evenly and allow to cool stood vertically so the heat rises and leaves even stress around the tube.
If for example you lay it flat to cool, the heat from the bottom side rises and the top side cools slower creating stress. Anything the glass touches also draws heat out of it so if its lay on a cool table that will suck heat from the bottom side creating even more stress.
Theres tons of super easy glass vapes to make even for non-glassworkers. The peace by treehouse being one of the simplest. A single boro tube and a block of fruit wood is all you need.
Good luck dude