If you want to see how a specific slide will behave when rendered, you have the option to use the slide preview. You find it in the Storyboard Editor as well as in the Script Editor (in the storyboard preview).
Click on the "Play" button in the bottom left corner of the slide.
Hover over the slide. Wait for it!
If you keep hover over the slide it will keep playing until you click on pause. If you stop Hovering over the slide, it will only play once.
In the Storyboard editor
In the Script editor
The maximum time (duration), the preview is able to show, is 15 seconds. So, if your slides duration is longer than 15 seconds, you will have to render the video to be able to preview it.