Read in rare cases growth plates cease to close. but what conditions/problems cause that and do adults eventually stop growing taller & at what point?

The reproductive: hormones estrogen/testosterone regulate the growth plates in both girls and boys. Estrogen, it turns out, drives this and if a boy has a genetic effect of estrogen production and estrogen sensitivity the growth plates fail to close on time. A pituitary growth hormone producing tumor diagnosed before growth plate closure would also result in very tall stature. Hope this helps:)