When sharing Windows folders on the network, it is possible to hide the shared folder from the list of shares. This can be done by adding a $-sign to the end of a share name.
It is important to mention that this does not really hide such shares from the network. If you ask a Windows machines for a list of its shares, then it reports all shares, including those with a $-sign. It are then the clients who filter out all shares that end in a dollar-sign.

So how can you get a list of all the hidden shares on a server?
Easy: open a DOS prompt and issue the following command: net view \\test-server /all

The output will be the following:

C:\Users\Lode>net view \\test-server /all
Shared resources at \\test-server

Share name                 Type  Used as  Comment
-------------------------------------------------------------------------------
ADMIN$                     Disk           Remote Admin
C$                         Disk           Default share
IPC$                       IPC            Remote IPC
Temp                       Disk
The command completed successfully.