I have to add my voice to VydorScope's on this matter. Sometimes writing happens (for those that work this way) without even the vaguest outline, sometimes it's a matter of seeing where the characters that sit in your head decide to go -
as you write.
The first novel in the series I am writing started with just an initial scene: two women watching a man grieving. It appeared in my head one night, I have no idea where the image came from. I had no idea who they were, I wasn't even clear on the source of the grief, although that part came quickly. I simply started writing to find out what happened (as strange as that may seem). The ideas expanded and grew from the characters that I saw there in that scene - as I wrote - until I found there was more than I could reasonably fit into a single book.
There does come a point (for me at least, I presume it is true for most) where you begin to see the direction you want things to take and you start nudging your characters in that direction. That first novel had various places where the writing stopped because what was going to happen next didn't just come from the characters and I had to force things along by picking a direction (I can still pick those places out and wonder if readers will too).
Things were a little different for the second book in the series, I had what I thought was an end-point for that novel ... but writing the book changed that ending considerably (and I had to rewrite the first half of it to clean up the winding path it took to get where it was going). I seem to be stalled on the third, despite (or because of?) knowing what I want to happen. It's almost as if the motivation for writing has been partly lost because I already know big chunks of the story. I have to get past that (my wife says so
).
There are obviously lots of hazards in the no-outline approach (just as there are in the outline approach), but I have used it because it's what seemed to be working for me - this time around anyway.