Visual Studio Windows Form Designer Freezes

If a Windows Form includes third-party controls, Visual Studio 2015 may freeze when trying to close the designer tab (or the application itself). The only way to get around it, is to kill the Visual Studio process, then delete the *.suo file. It used to be that the *.suo file was stored in the folder as the solution file. However, the *.suo file may be stored in a subfolder:

.\FolderA\SolutionA.sln
.\FolderA\.vs\FolderA\v14\.suo

If you delete the .suo file in the subfolder, then no tabs will open automatically when you open the solution in Visual Studio.