[Tellurium][1], 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!"


  [1]: http://m654z.github.io/Tellurium/