Leaving university after first semester and then going travelling

Are you studying at UFRGS? I don't think they would report you to the Policia Federal because you "skipped" your enrollment. Brazil has enough civil and criminal problems to pay attention to petty matters like that. Besides it's not the school's duty to cancel visas. It's the Policia Federal's duties.

Just don't overstay because of fines. Even then I've seen people who overstayed and was able to return to Brazil.

Brazil's borders are very porous where you can come in and out without problems. You can travel up to Asuncion, Paraguay and use the "ponte de amizade" (friendship bridge) where mass citizens of both Brazil and Paraguay cross daily. There no one will check even your passport. Just be sure to have your passport stamped by Paraguayan
border authorities upon entry so you can embark on a plane in Asuncion to other countries afterwards. Buses to Foz de Iguaçu, Parana is easy from any city in Brazil where  upon arrival at the rodoviario (bus terminal) you can get a taxi to the Ponte de
Amizade. Disembark and walk through the bridge following the Brazilians and go direct to the Paraguayan officers for passport stamp of entry. Tell them you'll stay for a month,
otherwise they´ll assume you´re there only for shopping for a duration of a day or so and passport is not needed. If you have overstayed don´t even talk to Brazilian authorities. They normally don't check passports in and out. If you're typically the gringo profile - fair haired with the blue eyes, don't you worry. In Parana that's very common like the other states - Santa Catarina and Rio Grande do Sul.

Porous borders:

Uruguay and Brazil: City of Rivera and Santana do Livramento. No border guards. Just an
    imaginary border line.

Paraguay and Brazil: Ciudad del Este (Cidade do Leste) and Foz do Iguaçu
                                     Juan Pedro Caballero and Ponta Porã, Mato Grosso do Sul

Bolivia, Peru and Brazil:  Boldebra, Bolivia, Iñapari, Peru and Assis Brazil. Checks occurs
    only @ Policia Federal & Customs (Alfandega) in Assis, Brazil but no one works after
    8pm.

Otherwise, go and ask your school like my compadre Pete told you. LOL!

I hope this helps and good luck!

robal