I use coffee pots Pyrex a hot plate, my electric hotplates are not the type with a spiral, they are cast iron tops with heating coil in grooves of the bottom of the Iron top, the heat is more even,this is important you dont have hot spots.
caution never change temperature on any glass item fast at all always gradually change temperature, never add cool liquids to hot glass, or solutions, or hot solutions to cold glass, its called thermal shock, the glass crystals do not always expand at the same rate so glass cracks or shatters, hot acids or spilling gold solutions, I also use a fiberglass tray under my hot plate, like a serving tray at a cafe. I have lab beakers also, you can order these at a reasonable price, if you do not have a good hot plate that distributes heat even an asbestos blanket or screen will help.
also you can use a sand bath, a pot of sand, a couple of inches thick in the pot and your heating vessel sits in this, it will not change temperature rapidly, and insulates your glass from the fire or electric element,it will get hot just wont do so at a fast rate and it distributes heat fairly evenly. some times I use an old automatic coffee maker, the burner on it will not boil but it is great for evaporating or heating solutions.
also I use these red high rubber type temperature heating pads, and I wire in a triac light dimmer to them, to control the temperature, they will get hot enough to boil , but I mainly use them for heating, I have large square pads I can sit an item to be heated on, or I have long one's that can wrap around jars or 5gal plastic buckets (careful you cannot heat plastic bucket too hot, so temperature control is important here). lab boiling flasks are also reasonable.
