I had the same problem when I made a mobile application with Phonegap.
I don't know how do avoid these flashes but when you've built a simple app with only a few screens you could implement all your HTML documents into one file like:
<html>
<body>
<div class="page" id="page-1">
Content of page one
</div>
<div class="page" id="page-2" style="display:none;">
Content of page two
</div>
<div class="page" id="page-3" style="display:none;">
Content of page three
</div>
</body>
</html>
Now you could switch between the contents of each container by making it visible/invisible for the user.
The idea behind this solution is that all of your app's content will get loaded once (at the beginning) and with jQuery you will switch between the content without these white flashes when the webbrowser has to render the new page the user has been redirected to.
This is a good solution only when your app does not contain too much contents.