What does “brontolio della caffettiera” mean in Italian?

Brontolare means to grumble or mutter — what a grumpy person does under their breath. Italians lend the same verb to the stovetop moka pot: when the water has pushed all the way up and the coffee is done, the pot starts to sputter and gurgle, and that noise is il brontolio della caffettiera. It is the kitchen’s built-in timer — the moment you hear it, you turn off the heat before the coffee scorches.

You will also hear the sound called il gorgoglio (the gurgle) or il borbottio (the bubbling/muttering); brontolio adds the human, faintly grumpy flavour, as if the pot were complaining. The everyday verb survives in un nonno che brontola (a grandfather who grumbles). Useful kit words from the same clip: la caffettiera / la moka (the pot), la valvola (the safety valve you fill the water up to), venire su (to rise/come up).