Possible Clues:

• Bubble gently just below boiling point
• A rise of about a couple of thousand will keep the pot boiling
• Keep the pot boiling
• Bubble on a low gas
• It's grand to get myself in here on the boil with the knight around
• Boil
• French lady grabbed by gentleman to feel rising anger
• Recipe direction
• That's myself in the rims with a little boil
• Is the South always in Germany with a boil?