How can a popup window appear and disappear while the user touches another object

Dear unity specialists,

I have a question regarding the popup window. My popup window should not be visible by default. It should appear after a part of a 3D object has been touched.
Since I am new in Unity/Vuforia/Scripting, I tried to watch tutorials, look for scripting examples, search in the forum. The pieces of code I could find unfortunately do not work for my project.
A short description of my project:
I have an image target which calls up my 3D object (works). I already have implemented raycasting and colliders for the parts of the 3d object (works at least while clicking on them, don’t know if it works while touching on them on the touch screen, probably LeanTouch could help here).
Now I want a text box or a popup window appear as a reaction on touching these colliders.
I tried to implement it with SetActive (true and false) but since I do not have any experience, I always get a lot of scripting errors.
I do not think it is something that cannot be realized with Unity and Vuforia.

So if somebody has time and idea how can it be implemented / how the script should look like, I would be very glad to read and try out your answers.
Thank you very much for your help!

There’s a good example in the docs:

You can add an if statement around it so it will only show when a certain boolean is true, and set that boolean when the user clicks a relevant object.

Example

	Rect windowRect = new Rect(50, 50, 200, 100);
	bool showWindow = false;
	void OnGUI() {

		if (GUILayout.Button("Give me popup!")) {
			showWindow = true;
		}
		if (showWindow) {
			windowRect = GUILayout.Window(0, windowRect, WindowProc, "Lilo Window");
		}
	}
	void WindowProc(int windowID) {
		GUILayout.Label("This is a pop up window");
		if (GUILayout.Button("Click to close Lilo Window")) {
			showWindow = false;
		}
	}

Thank you, sounds good!
Could you please write a code example?
Thanks!