What happens when a blank looks or steps into the Warp?

Im listening to the first Watchers of the Throne book right now and currently, a sister of silence is pondering an interesting question during a voyage through the Warp:

What would happen if she opened the blinds of the viewport and looked straight into the warp?

And that got me thinking, some machines and psykers are able to create portals straight into the warp. Either to pull something out or step into it to reach distant places.

So what if a blank would go into such a portal?