Related Clues:

• More than simmering
• Frothing
• Like really hot water
• Like a whistling teakettle
• Very, very hot
• In a tumultuous state
• Bring to ---
• Bubbling in the pot
• Hot and bubbling
• Quite stirred up
• Excitedly active
• Like geysers
• With lid rattling, say
• Bubbling, like hot water
• Bubbling, in a way