There was a term I read years ago, probably in my college course on childhood development, and for the life of me I cannot remember the actual term.
It describes a trip or experience where a pre-adult leaves their home for a period and experiences life away from their parents and household rules and such. After the trip/experience, the youth returns home. It's either implied or explicitly more than 1 day, and usually between a week and 6 months in length. Typical examples are summer camp and boarding school. It could also be an extended field trip, living with a relative during the summer, or going on a camping trip (provided their parents don't go on the same trip). Kiki's training period in a new city in Kiki's Delivery Service would fit the bill.
I think it started with ex-, but I could be wrong on that since the word often goes with "experience".
Example sentence: "My son is 12 now, and he should really have a(n) _____ experience soon."