You're allowed to rant about anything you like, without interruption, from the second you put the kettle on, to the second it pings because the water's boiled.
Obviously, the more water you put in the kettle, the longer you'll be able to rant, but you have to follow a couple of rules:
As the kettle gets louder, you have to get louder too. By the time the kettle is steaming, you have to be steaming too. If you're not, then you don't feel passionately enough about your rant-subject.
You also have to start off at the same volume as the kettle. You can't just launch off into a full-steaming rant if your kettle takes a while to warm up.
As Sting might say, let your kettle be your pilot.
OK, so you've really got going, the kettle's steaming, and so are you, you're shouting over the noise of the boiling water - but as soon as the kettle pings you have to stop. Then you can settle down with a nice cup of tea, and if there's anybody with you, you can decide whether they're allowed to ask questions. I recommend a 'One question per biscuit' rule. If they offer a biscuit and you accept, they're allowed to ask a question arising from your rant - but you're not allowed to go off on your rant again until it's time for a second cup of tea.
One more thought:
You guys in the US don't use kettles much do you? From what I've seen you tend to boil water by putting it in a pan on the hob. Can I just say - that is the strangest and most perverse national habit I've ever come across. I realise that perhaps you guys aren't into tea as much as we are in this country, but kettles aren't just for tea. I don't drink tea, and I find myself boiling the kettle all the time (and not just for ranting). How do you make pasta? How do you boil or steam vegetables? How do you poach an egg?