If you are just trying to learn UI development: try to develop a somewhat complex single page app without any framework (a GUI for a database for example). Don't do it as if you were just changing a document here and there with jQuery though. Try to approach it like a more typical UI development in another language (i.e. write your own mini component library that renders to the DOM, etc..)

By doing this you will see what problems you have to face, and the next time you see a framework you will catch up much more quickly on the good, the bad and how it fits.