When you got the server running via
mysql.server start
you should see the socket in /tmp/mysql.sock. However, the system seems to expect it in /var/mysql/mysql.sock. To fix this, you have to create a symlink in /var/mysql:
sudo mkdir /var/mysql
sudo ln -s /tmp/mysql.sock /var/mysql/mysql.sock
This solved it for me. Now my phpMyAdmin works happily with localhost and 127.0.0.1.
Credit goes to Henry