Like a link on a question/chat and click on it and it opens a new tab like when you click on a link in the yellow box when you ask a question.
Personally I dislike this. It's annoying for a site to force links to open in new tabs as you end up with loads of tabs.
If you want to open a link in a new tab you should decide that for yourself. If you want a quicker way, try middle-clicking on links to open them new tabs.