I think they actually used an English word, and they didn't think about boils like pimples but about the things that are boiling, a lot of people there, like a boiling pot? They study till they are 20 in Denmark: "Secondary education in Denmark (in Danish: ungdomsuddannelse, "youth education") usually takes two to four years and is attended by students between the ages of 15 and 20. Secondary education is not compulsory, but usually free of charge, and students have a wide range of programmes to choose from. Some education programmes are academically oriented, the most common being the Gymnasium. Others are more practically oriented, training students for jobs as e.g. artisans or clerks through a combination of instruction in vocational schools and apprenticeship." As I understand it, she was in year 3.