Why do streets turn corners in Boston?

Ok, I'm driving down the Tremont street, don't turn anywhere, only go straight at every traffic light. But for some strange reason, the green signs on traffic lights along my way turn into "Columbus" eventually. What the #$%ck?! Ok, calm down, stop, look at the map. Aha! For some reason, several traffic lights ago, Tremont street decided to go right instead of straight, and now I'm driving on Columbus instead. Wow!

Turns out, this is very common in Boston and happens just about every other block. And some streets are actually not even continuous - they're sprinkled in short stretches all over the city. Like the Boylston street, for example. Or Washington. I've been here for only a few months, but I already know two places that can be called "corner of Boylston and Washington". Go figure!

I always thought it to be self-evident that the very point of naming streets is to be able to determine and communicate one's location. But such "creative" layout pretty much defeats the purpose.