Here is a Newton gravity sand timer that puts on a mesmerizing show as time passes by. It is an hourglass inside a sealed cylinder filled with liquid. When the timer is flipped upside down, the hourglass rises to the top of the column.
The kit consists of an acrylic tube and a sand timer. Just bring your own water and table salt, and you are set. Grand Illusions has shared the above video to show how this works.