Yes, this is partially correct. I bottle it and then set it at room temp for a second ferment with sealed bottles. I do this second ferment anywhere from about 3 to 4 days up to 2 weeks (usually its about a week) for kombucha. I have never done 4 weeks. THat might give a tremendous amount of carbonation. With kefir water ive never had to do more than about 2 days to get it really carbonated. Kefir water gets fizzy fast and then can shoot all over the kitchen when opening.
Ive never had a bottle explode on me, but when i first tried this, i did let it ferment in the basement, as i was not familiar with if it could explode or not. I use thick walled glass bottles with a flip top. I have heard of people having exploding bottles though, so do be cautious with this and keep a close eye. I often will check my bottles by opening (outside if you are unsure) and seeing how fizzy it gets. It also greatly depends on the climate you live in and the temp. I live in Maine where its usaully pretty mild. I also brew - right now medicinal herbal beers - and am reading about people having explosions with those. One person talked about when a storm front came in and the barometric pressure dropped having many of his beer bottles that were fermenting explode on him.
HOpe some of that helps.