Maybe an investment in a stirring hot plate would be safer, we eliminated
bunsen burners from the lab years ago with fire hazard in mind, and
have a small magnetic stirrer with heating element.  Saved the day!
Use boiling beads (glass, wash and recycle) to disperse the
boiling solution and prevent a geyser effect of things boiling over.
Or a large magnet stirring vigorously, if you don't like the glass beads.

Still love my homemade Harris Hematoxylin with mercuric chloride, but alas
mercury disposal eliminated this solution from the laboratory and never cliked
the sodium iodate oxidized solution as well.  Our overall solution was to
purchase a commercial hematoxylin that withstands freezing during shipping,
but not everyone can afford this or likes the hands on approach.

Gayle Callis