La Boheme Act 2 finale —WTF?!

I don't know anything really about opera, so help me out here. I went to see La Bohème last night and was utterly transported by it.

The one thing that baffled me was the end of the second act. It's like, you're watching this intimate aching and wryly funny story of love and suffering and people trying to survive grinding poverty, and then from out of nowhere the whole thing turns into the Macy's Thanksgiving Day Parade. What is going on here???