How can I make my webdriver request multiple pages (or open multiple browsers) at the same time, concurrently?

All solutions I found on the internet waits until the previous session has finished loading and only then open a new instance of the browser.

I have tried selenium-webdriver, webdriverjs and wdjs, and none of them seem to be able to do multiple http requests for different pages asynchronously. Even solutions like this https://github.com/OniOni/wd-parallel-async wont work. They all open one at time.

Am I missing something?

PS: I don't want to run multiple browsers concurrently! I want to run multiple instances of the same browser.