Trace / monitor a variable at runtime?

I'm looking for a way to trace/monitor a variable at runtime (not for debugging) and throw certain events if it e.g. changes or falls out of the scope. Is there a .NET built-in way to do this? Like, not watching the variable itself and holding a reference to it, but the place in memory where it is allocated?

Ugly pseudo code:

public class Dummy {
    public void DummyMethod(int randomVar) {
        randomVar = 4;
    }
}

public class MyApp {
    static void Main() {
        var testVar = 1;
        SuperVariableWatcher.Watch(testVar);
        SuperVariableWatcher.NotifyOnChange += (sender, args) =>
           _logger.Write("variable bla bla has changed.");

        var dummy = new Dummy().DummyMethod(testVar);
             // since Dummy changes testVar, NotifyOnChange would now
             // be called, maybe with information about
             // who has changed it, what value did it contain before
    }
}

Of course I can hold a reference to it in SuperVariableWatcher and check for changes every nano-second, but even if it would work fast and reliable, I would then be unable to see if the variable is ready to be garbage-collected (because of no references to it) since I'd be the one that holds the reference.

I can think of something like angularJS $watch, however I'm not sure how it works internally.