I have, and I always thought it was a load of wank.
I decided last week I was going to make bread on Saturday, so I got ultra prepared and made a small starter dough on Wednesday. I figured I'd feed it for two days, and add it to the dough on Saturday etc etc.
Saturday came, and then Sunday, and I found I just didn't have time to make bread.
So I fed it a bit each night, and watched it grow and grow and grow.
It was pretty normal for the first few days - I fed it a bit of flour and water each night, gave it a stir and put it back to bed. It bubbled up like normal dough, and that was that.
Then it changed.
After the 4th night, it started to smell like super-beer. It also became soup-like in its consistency - I didn't over water it - it just went that way. A very thick soup, but soup nonetheless.
By tonight, the yeasty smell was quite overpowering. It was a good yeasty smell too - evocative of.....yeast. I almost ran down to the shop to buy some Coopers Pale Ale in order to compare the aromas.
I managed to find a bit of time tonight, so I mixed up a normal batch of dough and then scraped in the starter. The soupy starter made a wetter dough than usual, but I could handle that.
Into the oven it went...blah blah blah...and out came a super crusty, beautifully risen loaf. When I turned the oven on, I put a thick, cast iron skillet on the bottom shelf. It gets pretty hot as the oven warms up - perfect for making steam. Just before putting the bread in, I boiled up about 1 1/2 cups of water, put the dough in and then poured some boiling water over the skillet. That filled the oven completely with steam, and the steam is apparently what helps to form a crust. I checked the bread after 20 minutes, and poured in more hot water at that point.
I think I've finally got the knack. It's only taken about 10 years, 100 kilos of flour and endless totally or partially failed loaves. Boy, I'm a fast learner.