Something happens to photography when the subject is surrounded by nothing. The meaning of the photograph seems to changes. When the photo has simply black and a small area with a lit subject, the viewer sees nothing surrounding something.
The subject doesn't have to be underexposed, or have bright color, the subject needs to be an instance. An instance is something that counteracts the void, the feeling of emptiness. Take the meaning of void, and apply it to your subject.
In the above example, there's a shape of light in motion, in a frame of nothing. In the example above that, there was a moon caged by silhouetted leaves of a tree. Whether or not these shots work under a proper setting or foreground, the shots work under extreme simplicity.
There's an action or state of mind to be told in the small glimpse of light and color. Something I recommend in finding void shots is find something that either compliments or contrasts the black background that will surround it. This can be applied to the black and white flower, where it's finite amount of detail is extremely prominent from the emptiness of the shot. Another recommendation is to have something that comes into frame, but it seems like something lingers off the frame. In other words, really focus on composition. It can be really interesting when something trails off the image, and the frame shows a part of the subject that meets the void. That's probably the moral of each void shot: coming face to face with the void, the emptiness and simplicity that we can't imagine, but we still artistically express. If you want to see more examples: Here's a link. Thank you and Happy Shooting!