To clarify and expand the OP:
Since as far as anyone is able to remember, investments into public health and education have been few, and more than a bit of the money that does get invested is... "lost" among the way. While there have been some complaints, it was always minor and people simply treated it as a fact of everyday life.
Recently, due to the upcoming world cup and olympic games, a lot of money had to be spent on stadiums and other sports-related projects. The government attempted to justify this investment by citing the infrastructed required to host such events as improvements. Thing is, these improvements have only been limited to security and renovation of roads. To top it off, many of the projects went overbudget, costing over twice (and in some case over three times). Meanwhile, health and education have been once more ignored.
In order to try to make up for the lost money, the government increased taxes, especially bus fare prices. This was what sparked protests against the corruption and mismanagement of the country's finances. The protests started in the city of São Paulo, and was initally pacific. Poorly-prepared policemen , when taunted and provoked by attacks and acts of vandals hidden in the crowds, reacted with violence, causing massive confrontation in the city streets, with use of tear gas and rubber bullets from the police and rocks and molotov cocktails from the vandals.
This sparked reactions all across the country with similar protests erupting across all major cities. In some, the protests were completely peaceful, in other the majority of protesters managed to do so in peace with occasional conflicts with vandals and extremists, and in a few places it erupted into open violence.
The number of protests has since been steadily increasing, as has the number of people attending them. Unfortunately, more protests and more people also mean more violence from both sides. Meanwhile, president Dilma, instead of adressing the problems, simply keeps making empty speeches and having meetings with former-president Lula instead of, you know, her ministers or the state governors. Individual mayors have tried to remedy the situation by lowering taxes, but no action has yet to come from the federal government.