We had a reasonable budget when we did it in high school so went with
pyro for the bishop, obviously done by a professional. Hyde pulled out a hipflask (containing water), pours it over the bishop, lights a match and as he drops it the lights go to
blackout and a flame pot which is positioned just in front of the bishop fires.
As for the lab, we had a few bunsen burners with a gas tank in the set piece. Again, professional input required for an open flame onstage.
We had various coloured liquids in flasks
etc. It was enough to create a good
effect. The chemistry department had a lot of fun helping out and digging out all sorts of old interestingly shaped vessels to provide as
props.
Have posted a few images here to give some ideas:
http://imgur.com/a/pPaXs