Remember to add the stir bar when boiling your
It is very important that you DO NOT add the stir bar after the wort has been heated to boiling temperatures. Because the flask is so smooth the wort is actually superheating if the stir bar is not in there to provide nucleation sites. When you then add the stir bar later the wort will suddenly boil and shoot out of the flask. This happened to me once and I am lucky that neither I, or someone else got hurt. The wort sprayed 5 ft out of the flask and hit the cabinets.
That is exactly what happened to me.
I was lucky I was wearing paints (No Paints brewing reference).
Boiling wort was all over stove and me.
It shot out about 1 qt of wort from 4 liters.
I was so shocked that I did not know what to do first.
The casualty if this was that sticky wort got into electronics of the stove and we had to replaced it.
I was not hurt.
Live and learn.
So do not do it.