Set the target attribute of the link to _blank:
<a href="#" target="_blank" rel="noopener noreferrer">Link</a>
For other examples, see here: http://www.w3schools.com/tags/att_a_target.asp
Note
I previously suggested blank instead of _blank because, if used, it'll open a new tab and then use the same tab if the link is clicked again. However, this is only because, as GolezTrol pointed out, it refers to the name a of a frame/window, which would be set and used when the link is pressed again to open it in the same tab.
Security Consideration!
The rel="noopener noreferrer" is to prevent the newly opened tab from being able to modify the original tab maliciously. For more information about this vulnerability read the following articles:
与恶龙缠斗过久,自身亦成为恶龙；凝视深渊过久,深渊将回以凝视…
