1. Go to http://launcher.appsembler.com/openedx
2. Enter your email address and click "Launch demo site"
Your Open edX site will remain running for 2 hours and then will be shut down. (you'll get a warning email before it expires).
The technology using on the backend is Docker (https://registry.hub.docker.com/u/appsembler/edx/) which makes it easy to spin up new containers that use minimal resources.
This amazing website is made available thanks to Nate Aune and the people at Appsembler.