I have a question about boiling water for black tea. I have a whistling tea kettle that doesn't start to whistle until the water really starts to boiling (all of the water boiling fairly heavily).
Before it starts whistling though it will start to rumble a bit when the water is almost at the boiling point. When it starts to rumble you can see the water get a little bubbly but its not at a full boil.
So, should I wait until the kettle starts to whistle with a full boil or should I just let the water start to bubble a little bit before using it with the tea? I read about how having the water overboil is a bad idea, so I don't know if letting it get to a full boil counts as overboiling or not.