That's right! Now we arn't necessarily talking about the food here! But more the larynx.
When we talked about a "sandwiched" sound we are talking about laryngeal restriction in the throat, an over compression of the vocal cords, jaw tension, tongue retraction and tension in the breath.
Our aim with singing is to sing with an open throat. This consists of a loose jaw, some nasal resonance, no retraction of the tongue, the decompression of the vocal cords and to sing mostly in a neutral laryngeal position. Training to sing with an open throat provides the foundations for proper singing coupled with breath support and an understanding of vowel placement and modification.
Remember, if singing is causing you strain, discomfort, pain or tension - something is not right!