Suspending the current ssh connection

I'm new to Ubuntu and trying to learn ssh connections. I learned trick to suspend the current SSH connection and come back to localhost using:

~ + Ctrl-Z

When I press Shift+~, I suppose that the ~ shouldn't be visible until I press Ctrl-Z(which makes my ssh connection to be suspended and come back to localhost).

However at times it works as expected i.e ~ is not visible until I press Ctrl-Z. But at times ~ is been visible at terminal once I press the Shift+~ keys, which makes the suspending ssh impossible!

Am I missing something here.

Thanks in advance.