Q:

C# crash on runtime without exception

Ok this have been bugging me long enough now and have tried to Google it so here goes.
This is my code (I know it fails, that's the purpose):
public class Example
{
    private List<string> TestModes;

    public Example()
    {
        SetMode();
        TestModes = new List<string>();
    }

    public void SetMode()
    {
        TestModes.Add("This is a test mode");
    }
}

Here TestMode is null when I try to add a test case. What happens next is that the application stops and vanishes without any thrown exception or error of any kind. Am I wrong or shouldn't a NullReferenceException or something similar been thrown?
I use Visual Studio 2013 and have frankly no clue if this is a VS problem, C#/WPF problem or if it's just working as intended.
EDIT

Forgot to mention that it is running in Debug mode.
Everything under Debug -> Exceptions is checked

A:

This might be related to debugger configuration
In visual studio go to Debug -> Exceptions...
Make sure that all the "User-unhandled" checkboxes are checked.
To make sure you will break when the exception is thrown you could also check the box at Common Language Runtime Exceptions | Thrown
Hope this helps.

