Why NaCl not expected to produce a gas when tested with HCL?

NaCl is a strong salt of strong base and strong acid whereas HCl is a strong acid.

In the solution both dissociates in the solution into their respective ions as shown below:

NaCl ⇒ Na⁺ + Cl⁻

HCl ⇒ H⁺ + Cl⁻

Hence, the ions Na⁺, Cl⁻ and H⁺ are formed and there is no scope of reaction between them for a gas to evolve. They remain in the hydrated state in water.