The Pub people are doing experiments at their next meeting. This is what they wrote on Facebook:

Our next meeting will be at the new venue of the Brewery Tap. It has the advantage that we can use a side room so any bubbling experiments can be more easily contained We’ll either be in the room immediately on the right as you go in, or upstairs.

Then, as an afterthought:

If you bring something that starts bubbling that isn’t beer, the garden area outside would be more appropriate.

Maybe the fire station should be alerted?