Tellurium, 17 bytes

µHello, World!~^

Well, this is pretty easy to explain.

• µ starts reading the string
• ~ stops reading the string, and stores it in the selected cell.
• ^ outputs the selected cell's value, which is currently "Hello, world!"

Alternate version, non-competing (5 bytes)

This one uses the preinitialized variable !o, which expands to "Hello, World!".

µ!o~^